2^^ A Journal of Agricultural Research voi. xii, no. 6 



(8) The comparisons between the planted and unplanted duplicates 

 furnished valuable indexes of the inherent capacities of the soils to pro- 

 duce nutrients. 



(9) The accuracy of the methods of analysis an,d of the extraction 

 procedure employed was determined, and the mean and maximum errors 

 involved were estimated. 



(10) The amounts of the water-soluble nutrients obtained by varying 

 the ratio of soil to water were studied. The relationship of the com- 

 pounds extracted did not change essentially in the lower concentrations. 



(11) By comparison with freezing-point determinations the concen- 

 tration of the soil solution calculated from the water extract was ^hown 

 to be from two to four or five times as great as the actual soil solution. 



(12) Variations in the water extract were correlated with variations 

 in the freezing points of the same samples of soil. 



(13) From the results of the freezing-point determinations it is con- 

 cluded that variations in the water extract reflect actual changes in the 

 soil solution. 



(14) The results of the investigation show that large amounts of 

 water-soluble nutrients are developed by cultivation, fallowing, and bi- 

 ennial cropping, and demonstrate the soundness of these practices. 



LITERATURE CITED 

 (i) American Public Health Association. Laboratory Section. 



1912. STANDARD methods FOR THE EXAMINATION OP WATER AND SEWAGE. 



ed. 2, 144 p. Bibliography, p. 137-140. 



(2) BallEnEGGER, Robert. 



1913. SOIL STUDIES BY THE AID OF THEIR WATER SOLUTIONS. (Abstract.) IN 



Exp. Sta. Rec, v. 30, no. 6, p. 516. 1914. (Original article in 

 Foldtani Kozlony, v. 43, no. 7/9, p. 359-366. 1913. Not seen.) 



(3) BoGUE, R. H. 



1915. THE ADSORPTION OF POTASSIUM AND PHOSPHATE IONS BY T\TICAL SOILS OP 



THE CONNECTICUT VALLEY. In Jour. Phys. Chem., v. 19, no. 8, p. 664- 

 695, 13 fig. 



(4) BouYOucos, G. J. 



191 7. MEASUREMENT OF THE INACTIVE, OR UNFREE, MOISTURE IN THE SOIL BY 



MEANS OF THE dilatomETER METHOD. In Jour. Agr. Research, v. 8, 

 no. 6, p. 195-217, I fig. Literature cited, p. 217. 



(5) and McCooL, M. M. 



1916. THE FREEZING-POINT METHOD AS A NEW MEANS OF MEASURING THE CON- 



CENTRATION OF THE SOIL SOLUTION DIRECTLY IN THE SOIL. In Mich. 



Agr. Exp. sta. Tech. Bui. 24, p. 592H531, 2 fig. 



(6) Briggs, L. J. 



1902. FILTRATION OF SUSPENDED CLAY FROM SOIL SOLUTIONS. In U. S. Dept. 



Agr. Bur. Soils Bui. 19, p. 30-40, fig. 5. 

 (7) and McCall, A. G. 



1904. AN artificial ROOT FOR INDUCING CAPILLARY MOVEMENT OF SOIL MOIS- 

 TURE. In Science, n. s., v. 20, no. 513, p. 566-569. 



